Endoscopic surgery is a procedure by which operations on internal portions of a patient's body are performed on a minimally intrusive basis. Such surgery is accomplished by creating small incisions or ports in the patient's body through which various small, remotely controllable instruments may be manipulated. The procedure is accomplished visually with the aid of an endoscope, hence the name endoscopic surgery. Substantial advantages are realized from this form of surgery, including reduced trauma to the patient, less risk of death or complications, and rapid recovery.
The endoscope is a thin, tubular instrument utilizing fiber optics which allows a surgeon to remotely view internal body structures. As such, endoscopes typically have lenses located at an insertion or distal end, and an ocular or viewer located at the proximal end of the instrument outside of the body. Often times, the viewer takes the form of a video monitor. A light source is provided at the distal end to illuminate the internal body area. Various tools are used to perform the procedures associated with the surgery, as viewed by the endoscope. These tools often include retractors, irrigators, snippers, lasers, and the like.
Each of these tools, along with the endoscope itself, must be inserted in a patient's body through a port, as noted above. A port is comprised of an incision in the patient's body into which a hollow, tubular cannula is inserted. The cannula then serves as a conduit for receiving and supporting the endoscopic instruments.
An endoscopic port is created and the cannula is simultaneously placed therein by means of a trocar. A trocar is a surgical instrument having a sharp triangular point that enters the body through a small surgical stab incision. The cannula fits over the trocar and enters the incision along with it, such that after the port is created and the trocar is removed, the cannula remains in place to define the endoscopic port.
In a typical gallbladder surgery or cholecystectomy, as many as four to six ports must be made to accommodate the various endoscopic instruments needed to complete this procedure. Obviously, other types of endoscopic surgery will require more or fewer numbers of ports. Each port, including its associated cannula, must pass through the abdominal wall which includes the outer skin, a layer of fat, a layer of fascia or alternating muscle and fascia, and the peritoneum. The layers of fat and fascia may vary in thickness, depending upon the body location and whether the patient is asthenic or obese. Peritoneum is a strong, elastic membrane lining the walls of the abdominal cavity. Just below the peritoneum, however, lie several vital organs, such as the liver, stomach and intestines, and other sensitive tissues.
In cholecystectomies, as well as other types of endoscopic surgeries (appendectomies, etc.) a state of pneumoperitoneum is induced in the patient in order to provide an enlarged body cavity for manipulation of the endoscopic instruments and to avoid damage to internal organs and tissues. Thus, in pneumoperitoneum, the surgical area is insufflated with carbon dioxide. Insufflation is achieved initially with a so-called verese needle which is a large needle used to puncture the patient for the introduction of gas. However, some risk arises from this process in that the needle may be penetrated too far into the body, thus injuring the patient. On the other hand, if the needle does not pass at least through the abdominal wall when insufflation is initiated, other serious risks arise.
Immediately after the initial insufflation with a verese needle, a first endoscopic port is established via a trocar-guided cannula to permit internal visualization of the internal cavities. Thereafter, continued insufflation can occur through the cannula during surgery. As explained above, other endoscopic ports are necessary to accomplish the surgical procedure. Thus, the trocar, by providing a piercing guide for the cannula, which thereafter sustains pneumoperitoneum and defines a port for the surgical procedure itself, is critical to the success of endoscopic surgery.
However, the dangers of trocars are well recognized. In some cases, inadvertent visceral injury has occurred to vital organs through excessive trocar penetration. These dangers vary with the surgeon's experience, the dimensions of the trocar, and its site of insertion into the body cavity. Additional risks may arise from previous abdominal surgery, or peritonitis, in which adhesions may be responsible for complications associated with the insertion of the trocar and its associated cannula.
Thus, significant risks arise from the trocar establishment of endoscopic ports, especially the first port which is "blind." However, even with the aid of endoscopic vision, subsequent trocar insertion can also be a serious risk to the patient. This is due, in large part, to the combined toughness and elasticity of the abdominal wall which requires substantial manual force for trocar penetration. The built-up force, and subsequent momentum, which the surgeon develops in jabbing the trocar through the abdominal wall is difficult to reverse, thus leading, in some cases, to excessive penetration and injury. In order to limit the depth to which the trocar travels as it is pressed into the body, many surgeons use the ulnar border of the hand as a stop. Other surgeons press a finger along the axis of the cannula or trocar in order to limit the extent of travel. In both cases, however, the momentum of the insertion hand is simply transferred to these other limbs. This fact, combined with the flexibility of the abdominal wall which prevents it from successfully resisting penetration pressure, precludes these methods from offering an effective stop mechanism.
In order to reduce the risks of trocar usage, surgeons conventionally pinch a section of the skin with the hand not manipulating the trocar and lift it in the opposite vertical direction as the travel of the trocar. In other words, the abdominal wall is pulled upwardly with the intent of lifting the skin, fat, fascia, and peritoneum away from the vital organs below, thereby enlarging the void between the abdominal wall and such organs. This method is intended to provide a margin of error such that excessive penetration of the trocar will not reach the organs below the abdominal wall. This method, however, is also ineffective in many cases. First, it is difficult to get a good grip on the skin with the non-trocar hand, which is often the weaker hand of the surgeon. Secondly, the site of the finger pinch is, necessarily, somewhat removed from the site of the trocar insertion. Thus, only a portion or component of the lifting motion is transferred laterally to the exact location where the trocar is entering the body cavity. Thirdly, while the pinch method may be effective in asthenic persons, the thicker layers of fat in obese individuals render it highly unsatisfactory. Therefore, an improved method of trocar insertion is needed.
In light of the dangers of the above-described pinch method, specialized disposable trocars have recently been developed which are provided with spring loaded guards or shields for the sharp tip of the trocar. The shields are automatically deployed outwardly to cover the sharp tip of the trocar after abdominal wall penetration is achieved. Shield deployment, however, is sometimes delayed, and even a few milliseconds of delay can result in trocar injury. Furthermore, these trocars cost as much as several hundred dollars each and, since several must be used in a single endoscopic surgery, they result in greater expense. Thus, the use of shielded trocars is not a complete solution to this sensitive problem.
Another method for establishment of endoscopic ports, which does not require the use of a sharp trocar, is referred to as the "open laparoscopic" method. In accordance with this method, continuous visual control is maintained for insertion of a special open laparoscopic cannula. The key to this method is the use of an S-shaped retractor and Allis or Kocher type grasping forceps to laterally enlarge the initial incision and to lift the fascia. This procedure exposes the peritoneum and places it under tension so that it can be carefully pierced or incised. Although this method is relatively safe, it suffers from serious defects.
First, the procedure is lengthy and complicated, requiring a number of steps. In addition, insufflation pressure is lost due to the nature and length of time in which the port is open. Also, the port size is often larger than trocar induced ports, thus causing more discomfort and increasing recovery time for the patient. Thus, there is a need for a system of endoscopic port preparation which combines the advantages of a trocar without the attendant dangers.